A thin film transistor (Thin Film Transistor, referred to as TFT) are widely used in a liquid crystal display device (Liquid Crystal Display, referred to as LCD) and an active matrix driving type organic electroluminescent display device (Active Matrix Organic Light-Emitting Diode, referred AMOLED). As a result, thin film transistors affect the development of the display industry. However, in the conventional thin film transistor manufacturing method, formation of the thin film transistor has a problem that the leakage current is too large, and the leakage current influences the characteristics of the thin film transistor.